# Week Three Meeting: §3.3 – §3.4

This week’s Google Hangout (RSVP here) will cover problems/questions from week three of the syllabus:

• 3.3 Finite colimits in Set
• 3.4 Other notions in Set

If you’re joining us in progress, please feel free to add in any questions you might have about previous material as well – it’s never too late to join us all.

Those who aren’t able to jump into the hangout (due to hardware issues or the 10 person limit) are encouraged to chat within the hangout IM and follow along with the live stream. If you’re stuck and can’t make it, it will be archived on our YouTube Channel for later consumption.

## Gitter Instant Messaging Client

Group participant Steven Shaw has kindly set up an open chat/IM space for us using Gitter through GitHub (apparently one of the benefits of having some hard-core coders in the group).  Gitter is one of the few IM clients out there that allows the use of LaTeX.  You can log in with your GitHub account and feel free to post questions/thoughts there as well. Since it’s always up, feel free to use it during our online meetings or throughout the week.

Thanks Steven!

## Coming Up: Week Four §4.1-§4.2

We’ll have finished some of the introductory material and be getting into some new material, so those who were waiting for the serious material to start, get ready. We’ll be covering:

• 4.1 Monoids
• 4.2 Groups

## Online video

For those who aren’t aware, or haven’t checked recently, we’ve been adding a lot of material in the resources section of the site here.  In particular, I’ll draw your attention to the video section which includes The Catsters’ Category Theory Videos.

# Commutative Diagrams in LaTeX

## Overview

With my studies in category theory trundling along, I thought I’d take  moment to share some general resources for typesetting commutative diagrams in $\LaTeX$. I’ll outline below some of the better resources and recommendations I’ve found, most by much more dedicated and serious users than I. Following that I’ll list a few resources, articles, and writings on some of the more common packages that I’ve seen mentioned.

Naturally, just reading through some of the 20+ page user guides to some of these packages can be quite daunting, much less wading through the sheer number that exist.  Hopefully this one-stop-shop meta-overview will help others save some time trying to figure out what they’re looking for.

### Feruglio Summary

Gabriel Valiente Feruglio has a nice overview article naming all the primary packages with some compare/contrast information. One will notice it was from 1994, however, and misses a few of the more modern packages including TikZ. His list includes: AMS; Barr (diagxy); Borceux; Gurari; Reynolds; Rose (XY-pic); Smith (Arrow); Spivak; Svensson (kuvio); Taylor (diagrams); and Van Zandt (PSTricks). He lists them alphabetically and gives brief overviews of some of the functionality of each.

Feruglio, Gabriel Valiente. Typesetting Commutative Diagrams.  TUGboat, Volume 15 (1994), No. 4

### Milne Summary

J.S. Milne has a fantastic one-page quick overview description of several available packages with some very good practical advise to users depending on the level of their needs. He also provides a nice list of eight of the most commonly used packages including: array (LaTeX); amscd (AMS); DCpic (Quaresma); diagrams (Taylor); kuvio (Svensson); tikz (Tantau); xymatrix (Rose); and diagxy (Barr). It’s far less formal than Feruglio, but is also much more modern. I also found it a bit more helpful for trying to narrow down one or more packages with which to play around.

Milne, J.S. Guide to Commutative Diagram Packages.

### Spivak Pseudo-recommendations

David Spivak, the author of Category Theory for the Sciences, seems to prefer XY-pic, diagXY, and TikZ based on his website from which he links to guides to each of these.

## Resources for some of the “Bigger” Packages

Based on the recommendations given in several of the resources above, I’ve narrowed the field a bit to some of the better sounding packages. I’ve provided links to the packages with some of the literature supporting them.